Chassis suspension system for an articulated vehicle

ABSTRACT

A vehicle steering and chassis oscillation system with a steering mechanism for steering the vehicle through articulation and a chassis oscillation mechanism for controlling the transverse oscillation of the chassis through pivoting of a link in the articulating mechanism of the vehicle. The oscillation control of the chassis is accomplished through pivoting of a connecting link between the axle and the chassis to tilt the axis of articulation as the connecting link is pivoted. The oscillation of the articulating axis is generated by the suspension system for the vehicle.

This invention relates to a vehicle having articulated steering and moreparticularly to a vehicle having hydraulically actuated articulatedsteering with articulating bearings and a linkage interconnecting thevehicle chassis and one axle with an interconnecting link which ispivoted through hydraulic means to transversely oscillate thearticulating axis and provide a suspension system for the vehicle. Asingle front articulating axis may be used for steering and a singlemeans for oscillating the articulating axis or an articulating axis onthe front and the rear of the vehicle with an oscillating mechanismproviding a vehicle suspension system.

The conventional articulated vehicle is steered through a steeringmechanism which articulates the front frame and rear frames of thevehicle. The articulation is generally approximately at the midpoint ofthe vehicle. With the articulation at the midpoint of the vehicle, thearticulation causes the weight of the vehicle to swing transverselywhich may cause instability of the vehicle, particularly if the steeringcauses an extreme angularity of one frame to the other and particularlywhere the vehicle is on a hillside. To improve the maneuverability ofthe vehicle and increase the stability, the articulation of the vehiclecan be placed closer to the end of the vehicle and, furthermore, if thevehicle has two articulating axes where one is fore and the other is afton the vehicle, the stability of the vehicle can be improved. Oneadvantage is that the articulation about each articulating axis can behalf of the normal articulation required by a single articulating axisat the midpoint of the vehicle. Another advantage is that with doublearticulation crab steering can be accomplished which is advantageousparticularly when operating a vehicle on a hillside in which the terrainallows the vehicle to gradually slide downhill as it is operating. Thecrab steering moves both the front and the rear ends of the vehicleslightly uphill to compensate for downhill sliding as the wheels aregenerally rolling forwardly.

The use of an articulating linkage in which two bearings are verticallyspaced and connected to the vehicle chassis and a third bearing ispositioned between the axle means and a link interconnecting the chassiswith the axle means provides a flexibility in the articulating linkageto allow for slight rolling of the vehicle where at least two of thesebearings are spherical bearings. With this type of an articulatinglinkage and bearing structure, an additional oscillation control such asa suspension system can be provided to control pivoting of theconnecting link. With a suitable suspension system connected to thelink, the movement of the link can be controlled to oscillate thearticulating axis transversely of the vehicle. This, in turn, will causethe chassis to move transversely when the vehicle is traveling.

Accordingly, this invention provides for a hydraulic steering mechanismfor articulating the vehicle and a chassis oscillation mechanism whichallows oscillation of the articulating axis and the chassis transverselyto compensate for unevenness of the terrain upon which the vehicle isoperating.

It is an object of this invention to provide an articulated vehiclehaving an articulating axis on either the front or the rear of thevehicle or on both the front and the rear of the vehicle with controlledoscillation of the articulated axis and chassis.

It is another object of this invention to provide an articulatedsteering vehicle with front and rear wheel articulated axes and anoscillation control on each of the axes of articulation to provide asuspension system of the vehicle.

It is a further object of this invention to provide articulated steeringon a vehicle with vertically spaced articulated bearings and a linkbetween one of the articulated bearings and an axle means withoscillation control means connected to the link. The hydraulicoscillation control means tilts the axis of articulation when thesuspension system operates.

It is a further object of this invention to provide articulated steeringon the front and on the rear of a vehicle with oscillation controls oneach of the front and the rear axes of articulation to controloscillation through a linkage in the articulated steering mechanism bymeans of a suspension system.

The objects of this invention are accomplished by providing an axis ofarticulation on an articulated vehicle on the front of the vehicle andalso an articulating axis on the rear of the vehicle. For the purpose ofillustration, hydraulic means are provided for articulating each of theaxles relative to the vehicle chassis although any suitable motor meansmay be used. Each of the articulating axes are defined by an upper and alower articulating bearing. At least one of the articulating bearings isa spherical bearing pivotally connecting an axle with the vehiclechassis. The other of the articulating bearings is connected through alink to pivotally connect to the axle. One of the bearings connectingthe link is also a spherical bearing. Accordingly, a limited amount ofroll is permitted of the vehicle chassis relative to the axles of thevehicle. An oscillation control is provided by connection of the linkthrough spring and shock absorbers to the axle to provide controlledpivoting of the link. This, in turn, oscillates the articulating axistransversely and likewise controls the level of the vehicle chassisrelative to the axle. The hydraulic oscillation control may be allowedto float to permit the vehicle chassis to roll relative to the axles.

The preferred embodiments of this invention are illustrated in theattached drawings.

FIG. 1 is a side elevation view of a rough terrain fork lift vehicle;

FIG. 2 is a plan view of the rough terrain fork lift vehicle;

FIG. 3 is a three-dimensional view of a modification of the articulatingbearings and linkage and the hydraulic steering means with a suspensionsystem controlling oscillation of the articulating axis;

FIG. 4 is a modification of the articulating bearings, linkage andhydraulic steering means with a suspension means including a resilientarticulating link controlling the oscillation of the articulating axis;

FIG. 5 is an enlarged cross-section view of the lower spherical bearingfor the axle and chassis on the vehicle shown in FIG. 3;

FIG. 6 is a front cross-section view of the articulating bearings andthe chassis taken on line VI--VI of FIG. 1; and

FIG. 7 is a cross-section view of the articulating bearings oscillatedto tilt the chassis of the vehicle.

Referring to FIGS. 1 and 2, the vehicle 35 includes the chassis 14carried on the front axle 22 and rear axle 25 by articulating bearings.The extendible boom 32 is pivotally supported on the cradle 6 mounted onthe carriage 30 slideably mounted on the vehicle chassis 14. The cab 29defining the operator station is also supported on the vehicle chassis.The plurality of wheels 164 rotatably support the front and rear axles.

The vehicle chassis 14 can be oscillated transversely on the front axle22 and also on the rear axle 25. The connecting link 9 is pivotallyconnected through bearing 11 to the front axle 22 and pivotallyconnected to the chassis 14 through one of the articulating bearings 16.The link 9 can be pivoted transversely relative to the front axle 22 orthe chassis 14 by means of the hydraulic actuators 12 and 13. Thelinkage and oscillating mechanism will be subsequently described.

The vehicle chassis 14 is supported on articulating bearings 15, 16 onthe front and 17, 18 on the rear of the vehicle. The link 9 is pivotallyconnected through the articulating bearing 16 to the vehicle chassis 14.A pair of hydraulic actuators 12 and 13, of which 13 is shown in FIG. 1,pivot the link 9 to oscillate the vehicle chassis 14 transversely.Hydraulic actuators 12 and 13 are pivotally connected to axle 22 at 160and 161 and are pivotally connected to link 19 at 162 and 163. Thehydraulic actuators 20 and 21 articulate the axle 22 for steering of thefront end of the vehicle. Similarly, the hydraulic actuators 23 and 24articulate the link 26 to transversely oscillate the vehicle chassis 14.The hydraulic steering cylinders 27 and 28 steer the rear axle 25relative to the articulating bearings 17 and 18.

The chassis 14 carries the cab 29 and also slideably carries thecarriage 30 as shown in FIG. 1. The carriage 30 supports the tower 31 onwhich the boom 32 is pivotally mounted. The boom 32 is pivoted by thehydraulic actuator 33 mounted on the carriage. The front end of the boom32 carries the fork 34 for carrying a load.

A plan view of the fork lift truck 35 is shown in FIG. 2. The hydrauliccylinders 12 and 13 pivotally oscillate the link 19. The articulation isaccomplished through the hydraulic steering cylinders which pivotallyconnect the chassis 14 with the front axle 22.

FIG. 3 illustrates a modification of the invention in which theoscillating linkage 79 oscillating the articulating axis is controlledby a vehicle suspension system. The link 46 is pivotally mounted on thearticulating bearing 18 on the vehicle chassis 14. The link 46 is alsopivotally connected to the axle 25 by means of a bearing 38. Thehydraulic actuators 123 and 124 steer the vehicle through hydraulicmeans. Each of the links 41 and 42 include a shock absorber 43 as shownin link 42 and a spring 44. The springs 44 and 45 work in opposition toeach other to maintain a centered position of link 46 on the axis ofarticulation 47. Each end of the axle 25 is allowed to roll relative tothe chassis 38 due to roughness of the terrain. The roll is restrainedby the links 41 and 42 which absorb shock and allow the wheels to rideover the roughness of the terrain and provide a soft ride for theoccupant in the vehicle.

FIG. 4 is a modification of the articulating steering mechanism and thechassis oscillating mechanism shown in FIG. 3. The steering cylinders137 and 138 steer the vehicle by pivoting the chassis 38 relative to thefront axle 39. The link 77, however, is modified to accommodate themounting of a spring 51 embracing a shock absorber 52. Similarly, thespring 53 embraces the shock absorber 54. To provide balance in theoscillation control system, a shock absorber 140 and spring 141 are alsopositioned between the pivot pin opening 55 and the spring and shockabsorber mounting 56 of link 78. The steering of the vehicle is shown bya movement indicated by the arrow 48 and oscillation is shown by thearrow 156. A vertical ride reaction of the suspension system 58 is shownby the arrow 59.

FIG. 5 illustrates a cross-section view of the lower articulatingbearing 117 showing that the hydraulic cylinders 124 and 123 operatethrough the center of the bearing and do not cause any loading above orbelow the bearing 117 which may produce any torque on the articulatingaxis due to steering of the vehicle. Accordingly, steering of thevehicle would not create any force or moment which would affectoperation of the links 41 and 42 of the suspension system as shown inFIG. 3.

Referring to FIG. 6, the chassis 14 carries the bearing support 60 whichembraces the bearing race 61 forming a spherical socket receiving theball 62. The bearing race 63 is bolted against the shims 64 to form asocket for the ball 62. The seal 65 forms a seal between the bearingrace 63 and the front axle 22 permitting the front axle 22 to tiltrelative to the bearing support 60 of the chassis. A plurality of bolts,of which bolt 66 is shown, provides the fastening means for the bearingrace 63.

The cone section 68 integral with the ball 62 extends downwardly and isreceived within the conical recess 67 in the front axle 22. The bolt 69is bolted against the washer 70 to fasten the bearing element 68 to thefront axle 22. The bolt and washer are recessed within the annulus 71 asshown in FIG. 6.

FIGS. 6 and 7 show the articulating joints for the vehicle. Thearticulating axis 72 is defined by the upper articulating bearing 16 andthe lower articulating bearing 15. The lower articulating bearing 15forms a ball and socket joint.

The upper bearing assembly 16 includes a clevis 86 extending from thelink 9. The plate 87 extends from the chassis 14 and receives thebushing 88 which in turn embraces the spherical bushing 89. Bushing 88is retained by snap rings 100 and 101. The pin 90 is formed with anannular recess receiving snap ring 91 engaging the underside of theclevis 86 and extends through the spherical bushing 89. The upper end ofpin 90 is formed with an annular recess to receive snap ring 92. Thebearing assembly on its outer periphery is sealed by seals 93 and 94.Accordingly, the articulating bearings 15 and 16 define a common axisand this axis can pivot within either of the upper or lower bearingassemblies.

FIG. 7 illustrates a cross-section view of the articulating axis similarto FIG. 6. The chassis is tilted by oscillating the link 9 on the upperend of articulating axis 72. The tilting of the axis controls the levelof the vehicle chassis 14. Preferably, a single articulating axis willcontrol the level of the vehicle. If there is a second articulating axison the vehicle on the opposing end of the vehicle as shown, it may bepermitted to float so that a single axis controls the level of thechassis. If, however, the other axis of the vehicle is also used incontrolling the level of the vehicle, a suitable hydraulic system mustbe used so that the level of the vehicle is controlled through thesingle hydraulic system so both axes carry the load.

The operation of this device will be described in the followingparagraphs.

The articulation of the vehicle is controlled through the hydraulicactuators 20 and 21. Extension and contraction of the hydraulicactuators 20 and 21 pivot the vehicle on the articulating axis 72. Thevehicle is steered in this manner. An articulating axis may be providedon the front end and the rear end as well. By providing two articulatingaxes, the required angle of articulation for steering is reduced and thestability of the vehicle is increased. A suitable hydraulic system isprovided with a control valve for articulating the vehicle by hydraulicmeans as illustrated.

The oscillation of the articulating axis controls the level of thevehicle chassis. The axis 72 is oscillated by the operation of thehydraulic actuators 12 and 13. As the link 9 is articulated to theposition as shown in FIG. 2, the axis of articulation tilts about thelower bearing 15. As the articulating axis is tilted to a position shownin FIG. 7, the level of the chassis is tilted. This is accomplished bythe operation of the hydraulic cylinders 12 and 13 in response to acontrol valve in the hydraulic system. Accordingly, the level of thevehicle is controlled through the oscillation of the articulating axis.The leveling system may be used on a tractor on uneven terrain, or alift truck, a combine or any vehicle which requires a level chassis forideal operation. Accordingly, it can be seen that the articulation ofthe vehicle is for steering while the oscillation of the articulatingaxis transversely controls the level of the vehicle chassis.

FIG. 3 illustrates the suspension system for an articulated vehiclewhereby the front axle 25 tends to pivot and roll as the vehicle travelsover rough terrain. As the end 80 of the axle 25 lifts, the link 42compresses forcing the link 79 to pivot on the bearing 18. This in turntends to effectively shorten the distance between bearing 38 and 18while the link 41 is being compressed. The front axle 25 tends to rollrearwardly on its axis and the chassis 38 tilts slightly. The linkage 37including the link 79 and resilient links 42 and 41 allow movement ofthe chassis which absorbs the impact from the end 80 of the front axle21 to shift. Similarly, when the end 81 of the axle is raised orlowered, the linkage allows movement of the axle and permits a slightroll to accommodate the roughness in the terrain. Each of the links 41and 42 include a shock absorber which also absorbs shock as the vehicletravels over the terrain. Normally the springs 45 and 44 of the links 42and 41 maintain a centered position of the link 46 when the vehicle istraveling over a level surface.

Referring to FIG. 4, the suspension system is basically the same as thatshown in FIG. 3. When either end of the axle 82 is raised, the link onthis end tends to compress and shift the linkage toward the oppositeend. The difference in operation of this device is in that the two links76 and 78 on each of the arms of the link 83 will not only cause ashifting of the linkage but the center link 77 will also permit thefront axle to roll on its axis to a greater extent than that shown inFIG. 3. This linkage is more resilient in absorbing shock than thatshown in FIG. 3 since the axle is allowed to roll fore and aft moreeasily. The basic operation is the same and the springs in the link 76and 78 maintain a centered position of the linkage during normaloperation when the vehicle is traveling on a level surface.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. An articulated vehiclecomprising, means defining an axis of articulation including a vehiclechassis, an upper and a lower vertically spaced bearing mounted on saidchassis defining an articulating axis, at least one of said bearingscomprising a universally pivotal bearing, an axle means pivotallyconnected to the universally pivotal bearing, a link pivotally connectedto the other one of said bearings, a bearing pivotally connecting saidlink to said axle means, at least one of said bearings connected to saidlink comprising a universally pivotal bearing, a steering mechanismconnected between said chassis and said axle means selectively pivotingsaid axle means relative to said chassis for steering said vehicle, asuspension system providing a mechanism for selectively pivoting saidlink relative to said axle responsive to unevenness in the terrainincluding said link, a resilient member connected on each side of saidlink and connected to said front axle to normally bias said link to acentered position, each of said resilient members including a spring anda shock absorber connected between said link and said axle.
 2. Anarticulated vehicle as set forth in claim 1 wherein said link defines atransverse arm pivotally connected to each of said resilient members,said resilient members biasing said link and said chassis to thecentered position.
 3. An articulated vehicle as set forth in claim 1wherein said link includes resilient means compressably positionedbetween said pivotal bearing connecting said link to said chassis andsaid bearing connecting said link to said axle means.
 4. An articulatedvehicle as set forth in claim 1 wherein said link includes a spring anda shock absorber compressably positioned between said articulatingbearing connecting said link to said chassis and said bearing pivotallyconnecting said link to said axle means.
 5. An articulated vehicle asset forth in claim 1 wherein said link defines a T-shaped member, thecenter position of said link includes said bearings pivotally connectingsaid link with said axle means and said link with said axis.
 6. Anarticulated vehicle as set forth in claim 1 wherein said link defines aT-shaped member, the center position of said T-shaped member includes aspring compressably positioned on said link between said articulatingbearing connecting said link with said chassis and said link with saidaxle means.
 7. An articulated vehicle as set forth in claim 1 whereinsaid steering mechanism and said lower articulating bearing transmitsteering forces and a rection force lying in the same plane.
 8. Anarticulated vehicle as set forth in claim 1 wherein said link defines aT-shaped member, said resilient members and said upper articulatingbearing transmit forces lying in the same plane.
 9. An articulatedvehicle as set forth in claim 1 wherein said axle means and said upperarticulated bearing connecting said link to said chassis and said lowerarticulated bearing define spherical bearings to accommodate pitch androll of the suspension system on said vehicle.
 10. An articulatedvehicle as set forth in claim 1 wherein said link defines a T-shapedmember, and said resilient members connected to the arms of saidT-shaped member normally bias said link to a centered positioncoincidental to the longitudinal axis of said vehicle chassis.